Thermostat



April 23, 1940.

H. A. SMITH THERMOSIAT Filed April 3, 1939 w i i m.

Wad/wad Jkzzf/Z ATTORNEYS I Ahotherobjeotiiliobrovide scam Patented Apr.23, 1940 j p u OFFICE H n THEBMOST AT I Bows-rid. Smith, St. Louis, Moasaignor to Knapp-Monarch Company, St. Louis, Me a corporation ofMissouri s ru-s,m so,sen lno.zss.m

' (cl. sis-1a I element while the other ends thereof are con- An'obiectof my invention is to provide athermostat particularly designed tor tingpurposes'in connection with-a thermostat of a bread toaster or the like.

I thermostat for miaptiriratemperature nected by'a wire it to a switchblade II. 'A switch blade I. is adapted to cooperate with the blade II.The switch blades II and I. are normally separated and may be manuallyengaged with each other by swinging a plate l'l pivoted sive timer forelectric appliances such'asshown' in the copending application of JosephE. Brossea'u, Serial No'. 15,590; m d April 21; 1936, for

o a ons and temp ra or the'toaster 1n the usual manner intended.

i "More; ,it is my-objectto provide in a connection with atimer a'"'Iloperationin an'ovn type toaster whereby the' heater operatingthe'timer,a means to shorten 1 the initial fconsisting of a normallyopen compensating g n n m n 0 c mm mm th heater that 'nuringtne of. theheating perio o t e heater e n gized at a greater rate duflhglthelatter,v Various other objectsoi the invention and teagter'mostat andresistance SI with'the blmetal latch 2|.

through the medium of a contact 2' and a screw II. The blade 24 iselectrically connected with a wire 21, and to this wire an electricheater is is connected. The heater 2. is connected byawlre I.withthe'terminal II. The blade I! is also connected by a wire II andelement The foregoing described parts It to u, inclusive, form part oftheBrosseau" switch hereinbefore referred to, and form no part'of mypresent of; improvement ,5: the same will be brought out in the courseoi detailed specincationfafter which features deemed h m ms as m a nmanicularl js'etforth in the claims;

in well .L vention will now described in detail in connection with thedrawing illustrating oneiorm of the apparatus for embodying the featuresof improvements.

lnthedrawingzv. Figure. ils'ajbot, of a toaster including my thermostat;

Figure 21s a side elevation memrwim portions of the toaster broken away'and othe'rportions thereof shown in section;

Figure Figure 2 and ut 4 s n .e invention. 3 Ontheaccompanyingdrawinglhaveused the reference character h to indicate a base of abreadtoaster and C a casing thereof. Within the casing C a pair ofheating elements H are provided, one for each side of the slice of toastin the tic view of the Current supply terminals." andt! are prov videdfor the heating'elements H. The terminal II .II is connectedby awire isto one end of ects in view. m. in-

operationthe plate 11 a meme inthe position in Figure 4. The heatingelement-circuit flowingthrough the heater 2. warps the bimetal inventionwhich is an addition to theBrosseau switch. c

Briefly, the operation of the Brosseau switch is as follows: After aslice of toast is placed in the toasting chamber of thecasing C, theswitch lI-ll is closed and'during the'switch closing may now be tracedas follows: From'terznlnalf it through It, H, I, ll, ll, 22, 23,25, 20,20,11, It and 2! to the terminal ii. The electric current bar 24 to aposition for separating the screw 28 from the contact 25. This requiresa'certain timeperiod, which period varies dependent upon ambienttemperature affecting the bimetal blade 28. As the toaster warms up, theblade 23 moves to a position for shortening the time cycles so as toobtain substantially even toasting of the bread.- ,When the circuit isbroken across 3-26 then current flows through elements 30 and ii to thelatch 10 and switch blade l8 instead of through the elements 24, 2., 25,23 and 22. The heat 1 generated by the resistance element. 31 quicklywarps the latch 20 to unlatched position, thus permitting a spring I1 toswing the plate I! to position permitting the contact blade it to leavethe contact blade Ii, thus terminating the toasting period. r

I have found especially in. connection with oven type toasters that theinitial heating period is too long and tends-to bum-the flrst slice of65 toast. To overcome this deficiency I provide a compensatingthermostat which will now be. described. A post or screw I! is mountedon the top oi the base B (see Figure 2) and supports a bimetal blade 33and a spring blade 34. The blade 34 carries an adjusting contact screwII. The bimetal blade 33 is connected by a wire as with the wire 21,while the springblade II is connected by a wire 31 to a resistanceelement R. The resistance element R in turn is connected to the terminalII by a strap it which serves to support an insulating plate I! on which.the' resistance is wound. v

The compensating thermostat It is normally in open circuit position andis adjusted so'that during the initial heating period otthe toaster bythe heating element H it will close, thus connecting. the resistanceelement R in shunt or parallel with the heater 2!. This causes thecurrent from the terminal I! to divide through the resistance element Rand the heater 2., thereby reducing the amount or energiaation oi theheater so that its action on the bimetal element 24 will thereafter beslower.

By way of illustration, the initial heating cycle is usually two minutesin duration when the timer switch is used without my compensatingthermostat It. By arranging the thermostat it so that it closes otterabout forty seconds of this period, the heater ll will be initiallyheated at a higher rate during the forty second period so that theinitial timing cycle may be reduced, for instance. to a minute and ahalt. The adjusting screw II of course can be regulated so as to shortenthe initial period to the desired degree ior obtaining the same color oftoast for the first slice as for succeeding slices toasted in thetoaster and timed by the timer switch ll-lt.

I thus provide a simple mechanism for compensating iorinitially longtiming periods of the toaster, and the invention m be applied to otherelectric appliances ins'tead o! a toaster,

which has been shown merely by way of ilhntration. It is a comparativelysimple matter to test the toaster and adiust the screw ll so that thefirst slice of toast will receive substmtially the same amount'oi' heatas subsequent slices.

From the foregoing description of the means for accomplishing this end,it is apparent that I have devised a practical and emcient constructionfor carrying out the desired objects oi the invention as regards asimple and economical unit of the character described, and while theforegoing represents one of the preferred forms of embodiment of theinvention I desire to reserve the right to make whatever changes ormodifications may iairly tall within the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. The combination with a bread toaster having a thermostaticallyoperated timer including a temperature responsive element and anelectric heater therefor, said temperature responsive element beingeffective to terminate the timing period upon energization of saidheater for a predetermined period oi time; or means to reduce the timingof the temperature responsive element during the initial toasting periodonly comprising a normally open compensating ther-.

mostat in the toasting chamber of said toaster and responsive to heatradiated from the heating element of the toaster, said compensatingthermostat being adapted to move from open position during subsequenttoaster operations, a resbtanceelenent, said ccnspsnsaung thermostatbeim connected in series therewith, said compensating thermostat andsaid anceelementbeingconnectedinshuntwithsaid heater.

2.121embination withatoasterhavinga thermostatically operated timerincluding an electric heater for operating the timer toterdurmgsaidmitialtoasting periodandthereasteeremainclosodduringsubheating element, that it normally anormalpositiontoitsotherpositionsponsetoheatingbrsaidheatingelemsntdnring such initial heating period. aresistance element in circuit with said compensating thermostat. saidresistance element and compensating thermostat being shunt connectedwith said electrically operated device whereby closure of thecompensating thermostat reduces the current thereto for subsequentcycles of operation.

6. The combination with an electrical appliance having a heating elementand a thermostatically operated timer thereior including an electricallyoperated device; oi means to modify thetimingoi thetimerdurlng theinitial heating period of the heating element computing a compensatingthermostat responsive to the heat oi said heating element, saidcompensating thermostat being normally in one position and adapted tomove to and stay in its other position upon response to predeterminedheating by said heating element and closely repeated subsequent heatingcycles, said compensating thermostat being connected in parallel circuitwith said electrically operated device whereby closure oi thecompensating thermostat reduces the heating eflect 10 thereof on saidtimer during all oi said subsequent cycles of said appliance.

HOWARD A. SMITH.

